This invention relates to deposition and powder formation methods and more particularly to thin films and fine powders and fibers formation methods.
Thin films and methods for their formation are of crucial importance to the development of many new technologies. Thin films of less than about one micrometer (.mu.m) thickness down to those approaching monomolecular layers, cannot be made by conventional liquid spraying techniques. Liquid spray coatings are typically more than an order of magnitude thicker than true thin films. Such techniques are also limited to deposition of liquid-soluble substances and subject to problems inherent in removal of the liquid solvent.
There are many existing technologies for thin films deposition, including physical and chemical vapor deposition, plasma pyrolysis and sputtering. Collectively, these techniques are usable to produce thin films of many materials for a wide variety of applications, but it is still impossible to generate suitable thin films of many materials, particularly for thermally labile organic and polymeric materials. Some of these known techniques enable deposition of thin films having physical and chemical qualities, such as molecular homogeneity, which are unattainable by liquid spray techniques. Existing thin film technologies are often also inadequate for many applications due to high power requirements, low deposition rates, limitations upon substrate temperature, or the complexity and expense of deposition equipment. Hence, such techniques cannot be used economically to produce thick films or coatings having the same qualities as thin films. Also, most known thin film deposition techniques are mutually incompatible.
Accordingly, a need remains for a new surface deposition technique, which has the potential of allowing deposition of thin films not previously possible, with distinct advantages compared to existing thin film technologies.
Similar problems and a similar need exists in the formation of fine powders. Highly homogeneous and very fine powders, such as made by plasma processing, are very energy intensive and therefore expensive to make.